The present invention relates to a manually guided, portable tool or implement, especially a power saw, cut-off saw, or the like, and includes an internal combustion engine that is disposed in a housing had has a cylinder in which is formed a combustion chamber that is delimited by a piston that moves back and forth. By means of a piston rod, the piston drives a crankshaft that is mounted in an essentially plastic, pan-like crankcase.
With one known implement of this type (DE-OS 32 22 457), the plastic lower crankcase as well as the crankshaft journals and the journal sections thereof are secured in place on the cylinder in common via bolts that extend through the underside of the crankcase. Since during operation a not inconsiderable portion of the forces that occur in the region of the crankshaft is introduced into the crankcase and thus stress the latter, the crankcase must have a stable and hence complex configuration since a lack of sealing of the crankcase that occurs due to settling can adversely affect the ability of the implement to function.
It is therefore an object of the present invention to improve the internal combustion engine provided in a portable implement of the aforementioned general type in such a way that a permanent fixed connection is achieved between the cylinder and the plastic crankcase, whereby the overall height of the composite cylinder/crankcase is to be kept small.